In a cellular communications system, before transmitting downlink data to user equipment (UE) each time, a base station (BS) needs to send control information to the UE, to indicate, to the UE, information such as a time-frequency resource and a modulation and coding scheme that are used by the BS to transmit the downlink data, so that the UE can obtain, according to the control information, the downlink data transmitted by the BS. If there are multiple scheduled UEs, the BS may send control information of each scheduled UE to the UE.
For example, in a Long Term Evolution (LTE) system, control information of each UE may be encapsulated in downlink control information (DCI) carried by a physical downlink control channel (PDCCH), and one dedicated identifier of user equipment is added to the rear of each piece of DCI, so that the UE can obtain, by detecting a dedicated identifier of the UE, the control information for receiving downlink data.
With continuous evolution of a wireless cellular system, a future wireless cellular system not only needs to improve a total throughput, but also needs to support more users. Therefore, various multi-user technologies, for example, a conventional multi-user multiple-input multiple-output (MU-MIMO) technology and a non-orthogonal multiple access technology are certainly to be widely applied. In such an application scenario, with an increase of users, overheads for control information constantly increase, and particularly, repeatedly sending control information shared by users to the users causes a severe waste of system overheads.